In recent years, a streaming method has been widely used that plays back image data while receiving the image data via channels such as the internet.
In such streaming method, the problem is how to respond when the transmission delay is caused due to excessive communication load imposed on the channels (i.e. congestion) such as access being concentrated on the channels. Under a condition in which transmission delay occurs, a phenomenon in which image data necessary for playback does not arrive at a receiving side at a necessary time (this phenomenon is called reception buffer underflow) may occur.
Conventionally, an MPEG video recorder is known that stops decoding processing on image data, and continuously outputs an immediately preceding decoded image when the reception buffer underflow is caused. Specifically, the MPEG video recorder (i) compares an amount of an MPEG bitstream stored in the reception buffer with a predetermined threshold amount, (ii) skips the decoding processing when the amount of the MPEG bitstream stored in the reception buffer is lower than the threshold amount, and (iii) continues to output a decoding result of the MPEG bitstream that has been read from a bit buffer before the decoding processing is skipped.
In such way, the MPEG video recorder of the conventional technology skips decoding processing when the amount of the MPEG bitstream in the reception buffer is lower than the threshold amount (i.e. when it is highly likely that the reception buffer underflow will occur). This (i) allows the amount of the MPEG bitstream in the reception buffer to increase, (ii) prevents the reception buffer underflow, and (iii) causes video output to continue to be performed. Therefore, display continues to be performed, and a display image is not distorted.    Patent Document 1: Japanese published unexamined publication No. H8-331560